An implantable cardioverter-defibrillator (ICD) is an implantable device designed to deliver life saving defibrillation therapy to a patient in response to potentially deadly cardiac malfunctions. Often, when an ICD is implanted, it is tested to determine whether it can function for its purpose by observing whether the ICD can provide a shock exceeding the patient's defibrillation threshold (DFT). To perform this test, the ICD is implanted and the patient's heart is caused to fibrillate in the controlled environment of an operating room. Once fibrillation is induced, the ICD is expected to shock the patient back to a normal rhythm. If so, the ICD passes at least one round of the test. This procedure may be repeated. If the ICD fails to return the patient to normal rhythm, an attending physician will take steps, such as the use of an external defibrillator, to bring the patient's heart back to normal rhythm. After failure, the ICD is normally discarded, and the procedure may be aborted or a different ICD may be used.